linux-kernel - Re: [PATCH 1/1] tcp: Wrong timeout for SYN segments

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Date:	Sat, 25 Aug 2012 11:01:39 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Alexander Bergmann <alex@...lab.net>
Cc:	David Miller <davem@...emloft.net>, hkjerry.chu@...il.com,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1] tcp: Wrong timeout for SYN segments


> From: Alexander Bergmann <alex@...lab.net>
> Date: Fri, 24 Aug 2012 14:09:49 +0200
> Subject: [PATCH 1/1] tcp: Increase timeout for SYN segments
> 
> Commit 9ad7c049 changed the initRTO from 3secs to 1sec in accordance to
> RFC6298 (former RFC2988bis). This reduced the time till the last SYN
> retransmission packet gets sent from 93secs to 31secs.
> 
> RFC1122 is stating that the retransmission should be done for at least 3
> minutes, but this seems to be quite high.
> 
>   "However, the values of R1 and R2 may be different for SYN
>   and data segments.  In particular, R2 for a SYN segment MUST
>   be set large enough to provide retransmission of the segment
>   for at least 3 minutes.  The application can close the
>   connection (i.e., give up on the open attempt) sooner, of
>   course."
> 
> This patch increases the value of TCP_SYN_RETRIES to the value of 6,
> providing a retransmission window of 63secs.
> 
> The comments for SYN and SYNACK retries have also been updated to
> describe the current settings.
> 
> Signed-off-by: Alexander Bergmann <alex@...lab.net>
> ---

Acked-by: Eric Dumazet <edumazet@...gle.com>


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